The present disclosure relates to support surfaces for homecare, acute care and long-term care facilities and, in particular, a mattress replacement support surface capable to perform multiple protocols for the prevention and the treatment of pressure injuries and other medical complications.
Pressure applied to the skin against bony parts of the body disrupts the blood circulation through the capillaries, causes a decreased supply of oxygen and nutrition to the tissue and, if prolonged, may cause the development of pressure sores. Pressure and the duration of pressure have an inverse relationship. The NPUAP (National Pressure Ulcer Advisory Panel) defines a pressure ulcer as an area of unrelieved pressure over a defined area, usually over a bony prominence, resulting in ischemia, cell death, and tissue necrosis.
The average capillary blood flow pressure on healthy people is believed to be 32 mmHg. However, it is well documented that different anatomical locations have a large verity of pressure in their capillaries with values reduced for the elderly and by sickness. When external pressure is higher, blood flow is obstructed and circulation reduced or stopped, setting the stage for pressure sore to form.
In healthy, alert people, the discomfort produced by local pressure that might cause interruption of the blood flow, even as small as a wrinkle in a bed sheet, is normally severe enough to cause a small movement to relieve the pain. But if a person cannot sense or respond to the pain, the ischemia may be prolonged sufficiently to cause cell death resulting in a pressure sore.
Pressure sores do not originate in the skin but rather in the deep tissues where the pressures, due to internal bony prominences, are higher than on the skin itself. Also, muscle tissue is more sensitive than skin to pressure-induced ischemia and while the skin may be just discolored, the muscle underneath may be already necrotic.
Although there are other contributing factors such as sheer, friction, moisture, dryness of the skin resulting from poor nutrition, the most important factor in the development of pressure ulcers is unrelieved pressure. The level of pressure and the duration necessary to cause an ulcer have an inverse relationship. Therefore, the real solution rests in dealing with both parts of the equation: pressure and time.
The most common, but not exclusive sites of occurrence of pressure ulcers include the ischium (28%), the sacrum (17-27%), the trochanter (12-19%), and the heel (9-18%).
Individuals with mobility impairments that prevent independent repositioning are at high risk for developing pressure sores. It mostly affects the frail elderly and the immobile severe physically disabled, and costs the national budget billions of dollars each year. The NPUAP ranks four stages of pressure injuries, the lowest being “non-blanchable erythema” and the highest being “full-thickness skin and tissue loss”, with additional “unstageable pressure injuries” beyond this.
Support surfaces are classified by Medicare in three categories: Class 1 for passive support surfaces such as foam, gel, air mattresses; Class 2 for powered or active mattresses replacement and Class 3 for air-fluidized beds.
There are three basic methods utilized for prevention of pressure sores. One method is pressure redistribution (often confused with the term “low-air-loss” which according to NPUAP's definition is a feature of support surfaces that provides a flow of air to assist in managing the microclimate of the skin) where the purpose is to minimizing the risk for formation of pressure injuries by widely spreading the weight of the body over the support surface and reducing the pressure at the site of the bony parts of the body. Passive mattresses of foam, gel, water or air, some Class 2 powered support surfaces and Class 3 Air Fluidized bed strive to redistribute the pressure and reduce it from the risky parts of the body.
Another method utilized for prevention of pressure sores is alternating pressure. Support surfaces that perform this method are powered systems categorized by Medicare as Class 2. Typically, these support systems consist of a number of lateral, tubular air compartments, interconnected in two groups. One group having the even compartments interconnected, the other group having the odd compartments interconnected. When one group inflates, the other deflates. Some companies converted the tubular compartments to air cells of different shapes, but the principal of operation persisted: half of the cells inflate while the other half deflate. Although very popular, this method's efficacy is questionable since practically it reduces the area supporting the body to 50% or, as many manufacturers do, not deflating the part supposed to deflate to under the capillary pressure.
Another method utilized for prevention is the lateral rotation. There are not many beds in the marketplace that perform lateral rotation. In this method the body is rotated sidewise, thus moving the points of contact between the body and the support surface to new locations. The lack of automated systems performing lateral rotation is replaced in acute and long-term settings with strong recommendation to manually turn patients sidewise at least every two hours.
The most sophisticated systems for the prevention and treatment of pressure sores are Air Fluidized beds classified by Medicare as Group 3. These beds provide better immersion than most other pressure redistribution support surfaces in the market but are very heavy, noisy, expensive and inappropriate to perform CPR if cardiac arrest occurs. Air Fluidized beds are based on technology 40-50 years old.
There are numerous studies comparing systems representing one or other of these methods for prevention of pressure injuries to a standard hospital bed. There are, however, a limited amount of good, reliable studies comparing one of these methods to another. Most studies conclude that no evidence suggests that one method performs better than the others. There are not guidelines telling caregivers when or in what cases to use one method or the other and so patients are provided with whatever is available or cheaper, regardless efficacy.
Attempts have been made to combine the functionality of multiple systems. While many support surfaces claim to feature multiple functionalities, in most cases, these products perform one of the above described methods of prevention (discussed in greater detail below) combined with a low-air-loss method. Low-air-loss is a term introduced decades ago by a company that was praising the cover of its mattress relative to the quality of their competitors. A second conglomerate responded by punching holes in the air tubes and called it “the true low-air-loss”. The NPUAP responded in a set of meetings of the best clinicians in the nation stated that low-air-loss is not a method for prevention of pressure injuries but rather “a feature to assist in managing the microclimate of the skin.
As such, a problem that still exists is that no existing support surface is capable of performing each one of the three preventive methods (pressure redistribution, alternating pressure, lateral rotation) separately or in combinations chosen by the clinician. An additional problem which still exists is that no existing support surface is capable of performing an intense preventive procedure at several high-risk locations while the remaining of the support surface continues its ordinary preventive methods of operation. And yet another additional problem which still exists is that no existing support surface is capable of performing all three preventive methods in a combination chosen by the clinician while at the same time reducing the interface pressure in several locations in the support surface to lower than capillary pressure thus providing optimum conditions for better and faster healing of existing injuries.
To improve the efficacy of support surfaces, many companies provide pressure mapping using measurements taken intermittently by external systems such as Tekscan® and Xsensor®. None has a continuous, integral, displayed and recorded interface pressure measurement system of its own.